Effect of estrogen and progesterone on metabolism of apoprotein B in baboons.
To determine the metabolic mechanisms by which estrogen and progesterone alter levels of apoprotein B (apo B)-containing lipoproteins, 12 ovariectomized and hysterectomized baboons, maintained on a high-cholesterol (1.7 mg/kcal) and a high-fat (40% from lard) diet and divided into four groups, were treated with estrogen, progesterone, estrogen plus progesterone, and a placebo. After 12 wk, plasma cholesterol was unchanged in the control and progesterone groups but was reduced in the estrogen- and estrogen plus progesterone-treated groups. The reduction was primarily because of decreased low-density lipoprotein (LDL) cholesterol. LDL apo B levels decreased parallel to the LDL cholesterol. Very low-density lipoprotein (VLDL) and LDL apo B metabolism were studied using a double-label turnover study. Multicompartmental modeling suggested that LDL apo B was kinetically heterogeneous and that there exists an extravascular pool, perhaps consisting of hepatic remnants, that contributes significantly to LDL apo B transport. The model was used to estimate apo B production rates and residence times. VLDL apo B production was not affected by estrogen but was increased by progesterone. LDL apo B production was increased by both estrogen and progesterone. The residence time of LDL apo B was decreased by estrogen and estrogen plus progesterone but not by progesterone. Thus estrogen and progesterone have independent effects on apo B metabolism in baboons.
Kushwaha
R S
RS
Department of Physiology and Medicine, Southwest Foundation for Biomedical Research, San Antonio, Texas 78284.
Foster
D M
DM
Barrett
P H
PH
Carey
K D
KD
D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D007044:Hysterectomy; D007700:Kinetics; D008074:Lipoproteins / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008954:Models, Biological; D010052:Ovariectomy; D010215:Papio / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology*; D014280:Triglycerides / Q000097:blood
D001055:Apolipoproteins B; D004967:Estrogens; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D011374:Progesterone; D002784:Cholesterol